Rotary connector that prevents excessive temperature increase generated in a flexible cable

ABSTRACT

The rotary connector comprises a stationary housing  11  having a cylindrical portion  17  therein, a movable housing  12  having a cylindrical portion  19  therein provided on the stationary housing so as to be rotatable relatively thereto, and a flexible cable  14  accommodated within a housing section  13  formed between the stationary housing and the movable housing, in which the rotary connector further includes temperature detection means  41  for detecting the temperature of the flexible cable in a state of the temperature detection means being exposed within the housing section.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a rotary connector used aselectrical connection means for providing a heater device incorporatedin a steering apparatus of a motor vehicle or the like and an electronicdevice such as an air bag system equipped on a car body with anelectrical connection.

[0003] 2. Description of the Related Art

[0004] A rotary connector is generally incorporated in a steeringapparatus of a motor vehicle or the like and employed as electricalconnection means for providing a heater circuit employed in a steeringapparatus, an air bag circuit, a horn circuit or other switch circuits,all of which are incorporated in a steering wheel, with an electricalconnection. Furthermore, the rotary connector basically comprises a pairof a stationary housing and a movable housing, both being disposedcoaxially and connected together so as to be rotatable relatively toeach other, an annular space as a cable housing formed between a pair ofthose stationary and movable housings, a flexible cable housed in theannular space in a manner that the flexible cable can be wound andunwound, and lead blocks correspondingly connected to both ends of theflexible cable.

[0005] The flexible cable is constructed so that a plurality of (forexample, four pieces of) conductors made of a flat strip of extremelythin copper foil or the like, each conductor being interposed betweentwo sheets of insulating films as a flat strip of base film, aredisposed in parallel with each other and stuck to the insulating films.

[0006] The rotary connector having such basic construction is furtherfabricated as follows: fix the stationary housing to the car body whilefixing the movable housing to the handle member; and further, connectboth ends of the flexible cable to associated electronic devices on thesides of the car body and the handle member via respective lead blocksfixed to the stationary and movable housings; and thereby realizingelectrical connection means for providing a heater circuit device forsteering apparatus, an air bag system, a horn circuit and/or the likefor motor vehicle, with an electrical connection.

[0007] That is, the electrical connection means functions when apredetermined current flows through each of a plurality of conductors ofthe flexible cables.

[0008] However, in the above-described rotary connector, the flexiblecable is accommodated in a space formed between the stationary housingand the movable housing and is constructed so that a plurality ofconductors made of a strip of extremely thin copper (Cu) foil or thelike are stuck to the insulating films. As a result, the amount ofcurrent allowed to flow through each conductor cannot be made largerthan expected.

[0009] Additionally, in recent years, it has been seen a phenomenon as atrend that a vehicle primarily used in a cold district is equipped witha steering apparatus constructed such that a heater circuit device towarm a steering (handle) is incorporated therein. The heater circuitdevice used for the steering is required to supply a relatively largecurrent to a heater device to generate heat therein and therefore, ithas been required that the conductor of the flexible cable is able toallow a large current to flow therethrough.

[0010] However, when a large current flows through the conductor, such aproblem has been seen that the conductor generates excessive heat insome cases and owing to the increase in temperature of the conductorcaused by this excessive heat generation, the insulating film isdeformed, molten adhesively or the conductor is broken, leading tooccurrence of trouble in the function of rotary connector.

SUMMARY OF THE INVENTION

[0011] An object of the present invention is to provide a rotaryconnector capable of preventing excessive temperature increase generatedin a flexible cable by employing temperature detection means fordetecting the temperature of the flexible cable.

[0012] A rotary connector of the present invention comprises:

[0013] a stationary housing having a cylindrical portion;

[0014] a movable housing having a cylindrical portion and provided onthe stationary housing so as to be rotatable relatively thereto; and

[0015] a flexible cable accommodated within a housing section formedbetween the stationary housing and the movable housing;

[0016] in which the flexible cable is constructed such that both endsthereof are fixed to the stationary housing and the movable housing,respectively, and the rotary connector is further constructed to havetemperature detection means therein for detecting a temperature of theflexible cable in a state of the temperature detection means beingexposed within the housing section.

[0017] The above-described construction allows the rotary connector tomonitor the increase in temperature of the flexible cable due to thecurrent flow therethrough and therefore, the rotary connector is able todetect the increase in temperature of the flexible cable due to theexcessive heat generation via the temperature detection means andfurther appropriately control the excessive heat generation in theflexible cable by receiving a signal from the temperature detectionmeans, thereby realizing provision of a rotary connector capable ofpreventing deformation or fusion of insulating film.

[0018] Furthermore, the rotary connector of the present invention isfurther constructed such that the temperature detection means isprovided in one of the cylindrical portion of the stationary housing andthe cylindrical portion of the movable housing.

[0019] The above-described construction can prevent the occurrence ofphenomenon that the rotary connector becomes large by installation ofthe temperature detection means and further facilitate the installationthereof.

[0020] Additionally, the rotary connector of the present inventionfurther includes a holding member therein for holding the temperaturedetection means and the holding member is provided in one of thecylindrical portion of the stationary housing and the cylindricalportion of the movable housing.

[0021] The above-described construction allows for installation of thetemperature detection means via the holding member, thereby enhancingeasiness of installation and removal of the temperature detection means.

[0022] Moreover, the rotary connector of the present invention isfurther constructed such that the temperature detection means isprovided near one of fixing portions located between the flexible cableand one of the stationary housing and the movable housing.

[0023] The above-described construction allows for stable operation fordetecting temperature via the temperature detection means since theflexible cable moves little near the lead blocks in the event of theflexible cable being wound or unwound.

[0024] In addition, the rotary connector of the present inventionfurther includes a pressing member therein provided to face thetemperature detection means and press the flexible cable against thetemperature detection means.

[0025] The above-described construction allows for secure operation fordetecting the temperature of the flexible cable via the temperaturedetection means since the flexible cable is pressed against thetemperature detection means by the pressing member.

[0026] Furthermore, the rotary connector of the present invention isfurther constructed such that the pressing member has a structureindependent of the stationary housing and the movable housing and isprovided in one of the cylindrical portion of the stationary housing andthe cylindrical portion of the movable housing.

[0027] Compared with the case where the stationary or movable housingitself is directly installed in the rotary connector to replaceassociated pressing member, the above-described construction allows theoperation for installing and replacing the pressing member to becomeeasier and lower in cost since the pressing member has a structureindependent of the housing.

[0028] Moreover, the rotary connector of the present invention isfurther constructed such that the pressing member includes an elasticportion therein having elasticity and presses the flexible cable via theelastic portion.

[0029] The above-described construction allows the rotary connector tofurther securely press the flexible cable against the temperaturedetection means via the pressing member.

[0030] Additionally, the rotary connector of the present invention isfurther constructed such that the temperature detection means iscomposed of a temperature sensor.

[0031] The above-described construction allows for provision of alow-cost and performance-stable rotary connector since the temperaturesensor is inexpensive and is able to easily detect the desiredtemperature.

[0032] Furthermore, the rotary connector of the present invention isfurther constructed such that the temperature detection means iscomposed of a thermistor.

[0033] The above-described construction allows for provision of acompact and inexpensive rotary connector since the thermistor isinexpensive in addition to being compact.

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In the accompanying drawings:

[0035]FIG. 1 is an exploded perspective view of a rotary connector inaccordance with a first embodiment of the present invention;

[0036]FIG. 2 is a block diagram illustrating a first exemplary signalprocessing construction of procedure for processing a temperature signalfrom temperature detection means employed in the rotary connector inaccordance with the present invention;

[0037]FIG. 3 is a block diagram illustrating a second exemplary signalprocessing construction of procedure for processing a temperature signalfrom temperature detection means employed in the rotary connector inaccordance with the present invention;

[0038]FIG. 4 is an exploded perspective view of a rotary connector inaccordance with a second embodiment of the present invention;

[0039]FIG. 5 is a plan view of the rotary connector in accordance withthe second embodiment of the present invention;

[0040]FIG. 6 is a primary plan view of a first example employed in therotary connector in accordance with the second embodiment of the presentinvention, illustrating a connection status of the associated connectionpart between a flexible cable and a lead block;

[0041]FIG. 7 is a primary side view of the first example employed in therotary connector in accordance with the second embodiment of the presentinvention, illustrating a connection status of the associated connectionpart between a flexible cable and a lead block;

[0042]FIG. 8 is a primary plan view of a rotary connector in accordancewith a third embodiment of the present invention, illustrating aconnection status of the associated connection part between a flexiblecable and a lead block; and

[0043]FIG. 9 is a primary side view of the rotary connector inaccordance with the third embodiment of the present invention,illustrating a connection status of the associated connection partbetween a flexible cable and a lead block;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] A rotary connector in accordance with the present invention willbe explained below with reference to the accompanying drawings. FIG. 1is an exploded perspective view of a rotary connector in accordance witha first embodiment of the present invention.

[0045] Referring to FIG. 1, the overall construction of a rotaryconnector 1 explained hereinafter includes: a stationary housing 2; amovable housing 3 connected to the stationary housing 2 so as to berotatable relatively- thereto; a flexible cable 5 as a flat cable housedwithin a housing section 4 formed between the stationary and movablehousings 2, 3; a movable structure 6 rotatably disposed between thestationary and movable housings 2, 3; a lead block 7 connected to theflexible cable 5; and a temperature sensor 8 as temperature detectionmeans for detecting temperature of the flexible cable 5 while exposingthe body of the temperature sensor within the housing section 4.

[0046] The stationary housing 2 includes a cylinder-shaped outercylindrical portion 9, a circular bottom wall 10 formed on the end ofthe outer cylindrical portion 9 and a circular hole (not shown) formedin a central portion of the bottom wall 10. On the other hand, themovable housing 3 includes a cylinder-shaped inner cylindrical portion11 and an approximately annular upper wall 12 provided on one end of theinner cylindrical portion 11. The outer cylindrical portion 9 and theinner cylindrical portion 11 are coaxially disposed, and the movablestructure 6 is disposed in the housing section 4 located between theouter and inner cylindrical portions 9, 11.

[0047] The movable structure 6 being shaped like C-letter and made of asynthetic resin is disposed within the housing section 4 to be movablealong the circumference thereof, and the flexible cable 5 is disposedalong and wound around the circumferential surface of the movablestructure 6, and further, the flexible cable 5 positioned along thecircumferential surface of an opening end 6 a of the movable structure 6is disposed so as to be turned back in a reverse direction at thisposition (turned-back portion). That is, the flexible cable 5 at theposition of the turn-back portion (not shown) is disposed to form a loopalong the circumferential surface of the opening end 6 a constitutingone end of the movable structure 6.

[0048] The flexible cable 5 is formed so that a plurality of (forexample, four pieces of) conductors 5 b made of a flat strip of copperfoil or the like having an extremely thin thickness are stuck adheringto and interposed between two sheets of insulating films 5 a made of aflat strip of insulating tape such as polyethylene terephthalate (PET),while being disposed in parallel with each other. Outer ends of theconductors 5 b of the flexible cable 5 are electrically and mechanicallyconnected to the lead block 7 as a stationary joint portion fixed to theouter cylindrical portion 9 and have electrical connection with theoutside of the stationary housing 2 via the lead block 7.

[0049] Furthermore, inner ends of the flexible cable 5 are electricallyand mechanically connected to the lead block (not shown) as a movablejoint portion fixed to the inner cylindrical portion 11 and haveelectrical connection with the outside of the movable housing 3 via thelead block.

[0050] Subsequently, the constructions of the stationary housing 2 andthe temperature sensor 8 will be explained in detail.

[0051] First, as shown in FIG. 1, the stationary housing 2 made of asynthetic resin and formed by molding includes an outer cylindricalportion 9 being approximately shaped like cylinder, holding means 12formed in a predetermined portion of the outer cylindrical portion 9 andprojecting toward outside, a bottom wall 10 formed on the end of theouter cylindrical portion 9, and a circular hole (not shown) formed in acentral portion of the bottom wall 10.

[0052] Furthermore, the holding means 12 comprises a rectangularcut-portion 13 formed in the outer cylindrical portion 9, recesses 13 bformed in opposing inner walls 13 a of the cut-portion 13, a firstengagement portion 14 a being approximately shaped like rectangle andrecess, and formed in a thick block 14 of the outer cylindrical portion9, a slit-shaped guide portion 15 formed between the thick block 14 andthe outer cylindrical portion 9 while constituting a part of the housingsection 4, and a second engagement portion 16 being shaped like groovepenetrating the thick block in a direction in parallel with the axis ofthe stationary housing 2 and formed in a portion of the thick block 14,the portion being located at the position facing the cut-portion 13 ofthe thick block 14. Additionally, near the inner walls 13 a are formedsteps 13 c. Moreover, one end of the guide portion 15 is spatiallycommunicated with the inside of the outer cylindrical portion 9 and oneend of the first engagement portion 14 a is spatially communicated withthe cut-portion 13.

[0053] A holding member 17 made of a synthetic resin and formed bymolding comprises an approximately rectangular base section 18, collars20 projecting toward outside from one set of opposing side walls 19 ofthe base section 18, a pair of projections 21 formed on predeterminedareas of the side walls 19, a pair of hooks 22 extending beyond thelower ends of the side walls 19, and a recess 24 formed in one ofanother set of opposing side walls 23. Additionally, the upper end ofthe recess 24 is open. That is, the holding member 17 is formed asanother structure independent of the stationary housing 2.

[0054] The holding member 17 is to be mounted in the cut-portion 13 ofthe stationary housing 2 to fill in the cut-portion 13. This mountingoperation is performed so that the collars 20 of the holding member 17mate with the steps 13 c of the cut-portion 13 and the projections 21 ofthe holding member 17 are inserted into the recesses 13 b of thecut-portion 13, whereby the holding member 17 is integrally incorporatedinto the stationary housing 2.

[0055] In the above-described construction, the recess 24 of the holdingmember 17 is being mounted in the stationary housing so as to expose thesurface thereof toward the side of the guide portion 15 constituting apart of the housing section 4.

[0056] The temperature sensor 8 as temperature detection means isemployed for detecting temperature and for instance, is composed of athermistor, a bimetal or the like, and comprises an approximatelyrectangular detection unit 8 a and three terminal pins 8 b led from thedetection unit 8 a.

[0057] The detection unit 8 a of the temperature sensor 8 is held inplace within the recess 24 of the holding member 17 by pressing thedetection unit into the recess 24. In this case, the detection unit 8 ais mounted in the holding member so as to expose the surface thereof atthe temperature-detection side toward the side of the guide portion 15.

[0058] Furthermore, the terminal pins 8 b of the temperature sensor 8project toward outside beyond the holding member 17.

[0059] A printed wire board 25 made of an insulating plate has apredetermined circuit pattern (not shown) formed on at least one ofsurfaces thereof and six pieces of terminal holes 25 a formed inpredetermined portions thereof in addition to a pair of cut-portions 25b. formed in opposing sides thereof.

[0060] The printed wire board 25 is mounted on the lower end of theholding member 17 in such a manner that the printed wire board 25 ishooked on the hooks 22 that penetrate the cut-portions 25 b of theprinted wire board 25 and thereby integrally incorporated with theholding member 17. Furthermore, the terminal pins 8 b of the temperaturesensor 8 are inserted through the terminal holes 25 a and then fixed tothe circuit pattern by soldering.

[0061] A connector 26 includes three terminal pins 26 a and the terminalpins 26 a inserted through the terminal holes 25 a of the printed wireboard 25 are fixed to the circuit pattern via solder, whereby theconnector 26 and the printed wire board 25 are integrally incorporatedwith each other.

[0062] A pressing member 27 made of a synthetic resin and formed bymolding includes a support portion 27 a and a tongue-shaped elasticportion 27 b having elasticity and extending therefrom in a directionapproximately perpendicular to the support portion 27 a.

[0063] The pressing member 27 is mounted in the stationary housing sothat the support portion 27 a of the pressing member mates with and issupported by the second engagement portion 16 formed in the thick block14 and in this state, the elastic portion 27 b is being mounted so as toface the detection unit 8 a of the temperature sensor 8.

[0064] The lead block 7 includes an approximately rectangular basesection 7 a and four connection terminal leads 7 b formed by insertmolding and projecting toward outside.

[0065] The flexible cable 5 has already been explained above andtherefore, further explanation thereof will be omitted except that theflexible cable 5 is constructed so that the ends of the conductors 5 bare mechanically and electrically connected to the respective connectionterminal leads 7 b of the lead block 7 by, for instance, applyingsupersonic vibration.

[0066] Furthermore, the above-described lead block 7 is accommodated andheld in place within the first engagement portion 14 a of the stationaryhousing 2.

[0067] In the above-described construction, the temperature sensor 8 isbeing provided in the vicinity of the lead block 7.

[0068] Additionally, in this construction, the portion around the end ofthe flexible cable 5 is located within the guide portion 15, and isinterposed between the elastic portion 27 b of the pressing member 27and the detection unit 8 a of the temperature sensor 8. Furthermore, theflexible cable 5 is pressed against the detection unit 8 a by theelastic portion 27 b so as to make the detection unit 8 a securelycontact with the surface of the flexible cable 5.

[0069] The rotary connector 1 having such construction is finally usedas electrical connection means for providing a heater device forsteering apparatus, an air bag system, a horn circuit and/or the likefor motor vehicle, with an electrical connection after the followingassembling operation. That is, the stationary housing 2 is fixed to thecar body (not shown) and the movable housing 3 is fixed to the handlemember (not shown) and further, both ends of the flexible cable 5 areconnected to the associated electronic devices on the sides of the carbody and the handle member via the respective lead blocks 7 of thestationary and movable housings.

[0070] As can be understood, the flexible cable 5 functions aselectrical connection means when a predetermined current flows througheach of the plurality of conductors 5 b of the flexible cable 5.

[0071] The rotary connector 1 constructed as described above has atemperature detection and control mechanism as follows: a predeterminedcurrent flows through the associated conductors 5 b of the flexiblecable 5; and the temperature of the conductors 5 b is increased by thecurrent flow therethrough; and then, the temperature increase generatedin the conductors 5 b, i.e., the flexible cable 5 is continuouslydetected by the detection unit 8 a of the temperature sensor 8; andfinally, the flexible cable 5 is preferably controlled not toexcessively generate heat by the detection unit 8 a which performs theoperation for detecting the temperature of the flexible cable 5.

[0072] Next, a signal processing procedure for processing a temperaturesignal from the temperature detection means of the rotary connector inaccordance with the first embodiment of the present invention will beexplained.

[0073]FIG. 2 is a block diagram illustrating a first exemplary signalprocessing construction of procedure for processing a temperature signalfrom temperature detection means of the rotary connector in accordancewith the first embodiment of the present invention, and FIG. 3 is ablock diagram illustrating a second exemplary signal processingconstruction of procedure for processing a temperature signal fromtemperature detection means of the rotary connector in accordance withthe first embodiment of the present invention.

[0074] First, as shown in FIG. 2, a signal processing mechanismperformed within a vehicle via LAN (Local Area Network) cable comprisesa detection unit 61 as the above-described temperature detection meansfor detecting a temperature and outputting a temperature signalrepresenting the detected temperature, a transmission unit 62 forconverting the temperature signal from the detection unit 61 to a signalto be transmitted via a LAN cable and further transmitting (sending) thesignal, a reception unit 63 for receiving the signal from thetransmission unit 62 and converting the signal to the temperaturesignal, a control unit 64 composed of a Central Processing Unit (CPU) orthe like for arithmetically calculating the temperature signal from thereception unit 63 and outputting a control signal, a controlled unit 65composed of a heater circuit, a horn circuit or the like and controlledby the control signal from the control unit 64, and an input unit 66composed of a switching element or the like for transmitting ON/OFFsignal to the control unit 64.

[0075] In the above-described signal processing construction, thetransmission unit 62 and the reception unit 63 are connected with eachother via the LAN cable, and a variety of different multiple signals aretransmitted on the LAN cable.

[0076] In such a signal processing construction, the temperature of theflexible cable 5 is controlled as follows: the detection unit 61 detectsthe temperature of heat generated by the flexible cable 5 (refer to FIG.1); and then, the temperature signal outputted by the detection unit issupplied to the control unit 64 via the transmission unit 62 and thereception unit 63; and further, the inputted temperature signal and thepreviously defined reference temperature are compared by the controlunit 64; and thereafter, when the inputted temperature signal is lowerthan the defined reference temperature, the control unit 64 outputs acontrol signal to the controlled unit 65 such that a current iscontinuously supplied thereto and thus, the current is continuouslysupplied to the controlled unit 65.

[0077] On the other hand, when the inputted temperature signal is higherthan the defined reference temperature, the control unit 64 outputs acontrol signal to the controlled unit 65 such that the supply of currentthereto is temporarily stopped; and then, in accordance with the controlsignal, the controlled unit 65 is controlled such that the supply ofcurrent thereto is stopped; and as a result, the controlled unit 65 andthe flexible cable 5 supplying a current thereto are controlled so asnot to generate excessive heat.

[0078] In addition, subsequently, when the temperature increased by theheat generation in the flexible cable is lowered by stopping the supplyof current to the controlled unit 65 and the temperature detected by thedetection unit 61 as temperature detection means becomes lower than thedefined reference temperature, by receiving a control signal from thecontrol unit 64, the controlled unit 65 again begins to operate allowinga current to flow through the flexible cable to supply the current tothe controlled unit 65.

[0079] Furthermore, for instance, the input unit 66 composed of aswitching element through which a driver can manually input a signal isconstructed as follows: for example, as for a heater circuit, a signalfor controlling the heater circuit by an ON/OFF command is manuallyinputted to the control unit 64; and as a result, the heater circuit canbe turned on and off via the control unit 64.

[0080] Next, the signal processing construction within a vehicle in acase where the operation for controlling the temperature of the flexiblecable is performed directly via a wire harness cable is as follows: thebasic construction shown in FIG. 3 is the same as that of the previouslydescribed construction of FIG. 2, which employs the LAN cable, exceptthat the transmission unit 62 and the reception unit 63 employed in theconstruction of FIG. 2, both being connected to each other via the LANcable, are not provided in the construction of FIG. 3; and therefore,comprises a detection unit 71, a control unit 72, a controlled unit 73and an input unit 74, all of which have the same constructions as thoseof corresponding units employed in the first exemplary signal processingconstruction. That is, in the above-described construction, thedetection unit 71 and the control unit 72 are directly connected to eachother via the wire harness cable.

[0081] As the signal processing operation performed by the directconnection between the detection unit 71 and the control unit 72 via thewire harness cable is approximately similar to that performed in thecase where the connection between the above-described two units iscarried out via the LAN cable, the explanation of operation associatedwith the wire harness cable is omitted.

[0082] It should be noted that in the first embodiment, although thetemperature detection means is provided in the cylinder-shaped outercylindrical portion 9 of the stationary housing 2, the construction oftemperature detection means in accordance with the invention is notlimited to the above-described construction and therefore, thetemperature detection means may be provided in the inner cylindricalportion of the movable housing, the bottom wall of the stationaryhousing, the upper wall of the movable housing or the like so as toexpose the temperature detection means within the housing section.

[0083] Furthermore, in the first embodiment, although the holding memberfor holding the temperature detection means is provided in the outercylindrical portion of the stationary housing, the construction ofholding member in accordance with the invention is not limited to theabove-described construction and therefore, the holding member may beprovided in the inner cylindrical portion of the movable housing.

[0084] Moreover, in the first embodiment, although the pressing memberis formed of a material independent of the stationary and movablehousings and provided in the cylindrical portion of the stationaryhousing, the construction of pressing member in accordance with theinvention is not limited to the above-described construction andtherefore, the pressing member may be provided in the cylindricalportion of the movable housing or integrally formed with either thestationary housing or the movable housing.

[0085] Additionally, in the first embodiment, although the temperaturedetection means is provided near the lead block, the construction oftemperature detection means in accordance with the invention is notlimited to the above-described construction and therefore, thetemperature detection means may employ any construction as far as it isprovided so as to expose itself within the housing section.

[0086] Next, the rotary connector in accordance with second and thirdembodiments of the present invention will be explained with reference tothe accompanying drawings: FIG. 4 is an exploded perspective view of therotary connector in accordance with the second embodiment of the presentinvention; FIG. 5 is a plan view of the rotary connector in accordancewith the second embodiment of the present invention; FIG. 6 is a primaryplan view of the rotary connector in accordance with the secondembodiment of the present invention, illustrating the connection statusbetween the flexible cable and the lead block; FIG. 7 is a primary sideview of the rotary connector in accordance with the second embodiment ofthe present invention, illustrating the connection status between theflexible cable and the lead block; FIG. 8 is a primary plan view of therotary connector in accordance with the third embodiment of the presentinvention, illustrating the connection status between the flexible cableand the lead block; FIG. 9 is a primary side view of the rotaryconnector in accordance with the third embodiment of the presentinvention, illustrating the connection status between the flexible cableand the lead block. Note that the parts of rotary connector in thesecond and third embodiments and in addition, being the same as those inthe first embodiment are denoted by the same reference numerals used inthe first embodiment.

[0087] A rotary connector 80 in accordance with the second embodiment tobe explained with reference to FIGS. 5 and 6 basically comprises: astationary housing 81; a movable housing 3 connected to the stationaryhousing 81 so as to be rotatable relatively thereto; a flexible cable 5as a flat cable housed within a space 32 formed between the stationaryand movable housings 81, 3; a movable structure 6 rotatably disposedbetween the stationary and movable housings 81, 3; totally two leadblocks 7 each being connected to corresponding one of both ends of theflexible cable 5; a temperature sensor 33 as temperature detection meansfor detecting temperature of the flexible cable 5, the temperaturesensor being provided in the vicinity of the connection part of theflexible cable 5 and the lead block 7.

[0088] The stationary housing 81 includes a cylinder-shaped outercylindrical portion 82, a circular bottom wall 83 provided on the end ofthe outer cylindrical portion 82, and a circular hole 84 formed in acentral portion of the bottom wall 83. On the other hand, the movablehousing 3 includes a cylinder-shaped inner cylindrical portion 11 and anapproximately annular upper wall 12 provided on one end of the innercylindrical portion 11. The rotary connector having such constructionsof stationary and movable housings is further constructed such that theouter cylindrical portion 82 and the inner cylindrical portion 11 arecoaxially disposed, and an annular housing section 4 as a space 83 isformed between the outer and inner cylindrical portions 82, 11. Inaddition, within the housing section 4 is disposed a movable structure6.

[0089] An approximately rectangular temperature sensor 28 functions astemperature detection means and is composed of, for instance, athermistor.

[0090] The temperature sensor 28 is mounted on the flexible cable 5 inthe vicinity of the end thereof by appropriate means such as bonding todetect the temperature of conductors 5 b of the flexible cable 5. Inthis construction, the temperature sensor 28 is mounted so that thesurface thereof for detecting temperature is disposed to face theflexible cable 5 for the temperature sensor to securely be able todetect the temperature of the respective conductors 5 b.

[0091] Subsequently, the-connection status between the flexible cableand the lead block of the rotary connector in accordance with the secondembodiment of the present invention will be explained in detail.

[0092] The connection status between the flexible cable and the leadblock will be explained with reference to FIGS. 6 and 7 as follows: aflat strip of flexible cable 5 as a flat cable comprises two laminatedfirst and second lengthy insulating films 29, 30 as a base film made of,for instance, a resin material such as polyethylene terephthalate (PET)and formed like a thin film in addition to being shaped like a flatstrip; and four pieces of conductors 5 b made of copper foil or the likeand shaped like flat strip, the conductors being almost entirelyinterposed between the first and second insulating films 29, 30, andbeing formed equally spaced from each other and in parallel with eachother in addition to having equal width dimension respectively.

[0093] Furthermore, each conductor 5 b has a base conductor 5 c entirelyinterposed between the first and second insulating films 29, 30, and anexposed conductor 5 d stripped of the insulating films and projectingtoward outside from the ends of the first and second insulating films29, 30 while extending from the base conductor 5 c.

[0094] Additionally, a flat strip of holding film 31 made of PET or thelike is stuck adhering to one surface of the end of each exposedconductor 5 d to hold the freely movable end thereof.

[0095] Such construction around the exposed conductor is found at eachof both ends of the flexible cable 5.

[0096] Moreover, the temperature sensor 28 is mounted on the firstinsulating film 29 in the vicinity of the end of the first insulatingfilm 29 of the flexible cable 5 by appropriate means such as bonding todetect the temperature of the conductors 5 b of the flexible cable 5. Inthis construction, the temperature sensor 28 is mounted so that thesurface thereof for detecting temperature is disposed to face the firstinsulating film 29 for the temperature sensor to securely be able todetect the temperature of the conductors 5 b, respectively.

[0097] In addition, the lead block 7 includes a base section 32 made ofan insulating material and four pieces of connection terminal leads 33formed in the base section 32 such as by insert molding. Furthermore,the approximately rectangular base section 32 is, for example, made ofan insulating synthetic resin and formed by molding, and has arectangular through hole 32 a therein around the central portionthereof.

[0098] Furthermore, on the side of the front end of the base section 32(upper side of FIG. 7 when viewing the paper from a direction verticalto the paper) is provided a tilting table portion 32 b projecting towardoutside from the upper surface of the base section 32.

[0099] The connection terminal leads 33 made of an electricallyconductive plate of metal such as a copper and formed by press moldingin addition to having a predetermined width dimension comprises fourpieces of connection parts 33 a arranged being equally spaced from eachother and external terminals 33 b extending toward outside from theconnection parts 33 a. The connection terminal leads 33 are formedwithin the tilting table portion 32 b of the base section 32 by insertmolding so as to be integrally incorporated into the base section 32. Inthis case, the width dimension of the connection terminal lead 33 isapproximately equal to those of the base conductor 5 c and the exposedconductor 5 d of the flexible cable 5.

[0100] In the above-described construction, an approximately centralportion of the connection parts 33 a of the connection terminal leads 33is formed bridging across the through hole 32 a and further, the basesection 32 and the connection parts are formed such that the surface ofthe connection parts 33 a on the side of the rear end thereof (lowerside of FIG. 7 when viewing the paper from a direction vertical to thepaper) and the surface of the base section 32 become coplanar.

[0101] The assembling operation for connecting the flexible cable andthe lead block of the rotary connector will be explained below.

[0102] As shown in FIGS. 6 and 7, the flexible cable 5 is disposed onthe lead block 7 such that the exposed conductors 5 d of the flexiblecable 5 is laminated on the upper surface of the base section 32 of thelead block 7.

[0103] Furthermore, in the above-stated construction, the connectionparts 33 a of the lead block 7 and the exposed conductors 5 d of theflexible cable 5 are provided so as to correspondingly be laminatedtogether and face each other, and further the exposed conductors 5 d aredisposed above the through hole 32 a of the lead block 7.

[0104] In addition, the connection parts 33 a and the laminated exposedconductors 5 d are mechanically and electrically connected to each otherrespectively by appropriate means such as ultrasonic bonding or thelike.

[0105] Moreover, in the above-stated construction, the temperaturesensor 28 provided on the flexible cable 5 are mounted on an area of theflexible cable 5, the area corresponding to a position of the flexiblecable 5 being placed on the base section 32 of the lead block 7.

[0106] Additionally, the conductors 5 b and the connection terminalleads 33 are correspondingly and individually connected to each other.

[0107] The above-described connection construction allows the conductors5 b to pass a predetermined current therethrough, respectively.Therefore, the current flows through the respective conductors 5 b andthen the temperature thereof increases.

[0108] The rotary connector 80 having such construction is furtherfabricated as follows: fix the stationary housing 81 to a car body (notshown) while fixing the movable housing 2 to a handle member (notshown); and further, connect both ends of the flexible cable 5 torespective electronic devices on the sides of the car body and thehandle member via associated lead blocks 7, 7 provided in the stationaryand movable housings; thereby, realizing electrical connection means forproviding a heater circuit device for a steering apparatus, an air bagsystem, a horn circuit or the like for motor vehicle with an electricalconnection

[0109] That is, the electrical connection means functions when apredetermined current flows through each of four conductors 5 b of theflexible cable 5.

[0110] The above-described construction of the rotary connector 80ensures the secure detection of temperature of the flexible cable 5 inthe following manner. That is, a predetermined current flows througheach of the conductors 5 b of the flexible cable 5, and then, thetemperature thereof increases by the current flow therethrough, andfurther, even when the flexible cable is wound or unwound, thetemperature sensor 28 detects the temperature increase generated in theconductors 5 b, i.e., the flexible cable 5, without the influence ofvibration or deformation thereof. Operation for detecting thetemperature of the flexible cable 5 allows the rotary connector to beable to preferably control the flexible cable 5 so as not to excessivelygenerate heat.

[0111] Next, the connection status between a flexible cable and a leadblock of the rotary connector in accordance with the third embodiment ofthe present invention will be explained.

[0112] As shown in FIGS. 8 and 9, the construction of a flexible cable34 is similar to that of the flexible cable 5 employed in the previouslydescribed second embodiment and therefore, the explanation associatedwith the flexible cable is omitted.

[0113] As for the construction of a lead block 35, as shown in FIGS. 8and 9, the construction thereof different from that of the lead block 7employed in the previously described second embodiment will beexplained.

[0114] Different from the base section 32 employed in the secondembodiment, a base section 36 of the lead block 35 has an approximatelyrectangular recess 35 c therein on the rear end side thereof (lower sideof FIG. 9 when viewing the paper from a direction vertical to thepaper). Within the recess 35 c is provided an approximately rectangulartemperature sensor 37 as temperature detection means, and in theabove-described construction, the temperature sensor 37 is provided sothat the upper surface thereof becomes coplanar with the surface of thebase section 36.

[0115] Additionally, in the state of the temperature sensor 37 beingprovided and accommodated within the recess 35 c of the base section 36,the flexible cable 34 is provided on the upper surface of the basesection 36 of the lead block 35 in a manner similar to that ofpreviously described construction and exposed conductors 5 d aremechanically and electrically connected to associated connection parts38 a. In this case, the flexible cable 34 is provided such that thesurface of a second insulating film 30 of the flexible cable 34 makescontact with the upper surface of the temperature sensor 37, therebyallowing the temperature sensor 37 to securely detect the temperature ofthe conductors 5 b of the flexible cable 34, respectively.

[0116] As is described above, the rotary connector employed in thisembodiment in accordance with the present invention is constructed sothat the temperature sensor 37 is able to continuously detect thetemperature increase generated in the flexible cable 34.

[0117] The processing of a temperature signal from the temperaturedetection means that is employed in the rotary connector of the secondand third embodiments in accordance with the present invention isperformed following the signal processing construction shown in FIGS. 2and 3.

[0118] It should be noted that although the construction thattemperature detection means is mounted on an area of a flexible cable,the area corresponding to a position of the flexible cable being placedon a base section of a lead block, or is directly mounted in the leadblock is employed in the above-described second and third embodiments,the construction of temperature detection means in accordance with thepresent invention is not limited to the above-described construction andtherefore, the construction that temperature detection means is providednear a connection part located between a flexible cable and a lead blockmay be employed.

[0119] A rotary connector according to the present invention isconstructed so that temperature detection means is provided therein in astate of the temperature detection means being exposed within a housingsection formed between a stationary housing and a movable housing andthe rotary connector is thereby equipped with the capability to monitorthe increase in temperature of a flexible cable due to excessive heatgenerated by current flow therethrough. That is, the rotary connectordetects the temperature increase due to the excessive heat generation inthe flexible cable via the temperature detection means, and thenpreferably controls the flexible cable not to excessively generate heatby receiving a signal from the temperature detection means, therebyrealizing the provision of rotary connector capable of preventingdeformation or fusion of insulating film.

[0120] Furthermore, the rotary connector according to the presentinvention is constructed such that the temperature detection means fordetecting the temperature of the flexible cable is provided near theconnection part between the flexible cable and the lead block andtherefore, is able to detect and monitor the temperature increase due toexcessive heat generated by current flow through the flexible cable.Thus, the present invention can provide an advantageous rotary connectorcapable of appropriately controlling the excessive heat generation inthe flexible cable by detecting the temperature increase due toexcessive heat generated in the flexible cable via the temperaturedetection means and then receiving an associated signal from thetemperature detection means.

What is claimed is:
 1. A rotary connector comprising: a stationaryhousing having a cylindrical portion; a movable housing having acylindrical portion and provided on said stationary housing so as to berotatable relatively thereto; and a flexible cable accommodated within ahousing section formed between said stationary housing and said movablehousing, wherein both ends of said flexible cable are fixed to saidstationary housing and said movable housing, respectively, and saidrotary connector further comprises temperature detection means fordetecting a temperature of said flexible cable, said temperaturedetection means being exposed within said housing section.
 2. The rotaryconnector according to claim 1, wherein said temperature detection meansis provided in one of said cylindrical portion of said stationaryhousing and said cylindrical portion of said movable housing.
 3. Therotary connector according to claim 1, wherein said rotary connectorfurther comprises a holding member for holding said temperaturedetection means and said holding member is provided in one of saidcylindrical portion of said stationary housing and said cylindricalportion of said movable housing.
 4. The rotary connector according toclaim 1, wherein said temperature detection means is provided near oneof fixing portions located between said flexible cable and one of saidstationary housing and said movable housing.
 5. The rotary connectoraccording to claim 1, wherein said rotary connector further comprises apressing member provided to face said temperature detection means andpress said flexible cable against said temperature detection means. 6.The rotary connector according to claim 5, wherein said pressing memberhas a structure independent of said stationary housing and said movablehousing and is provided in one of said cylindrical portion of saidstationary housing and said cylindrical portion of said movable housing.7. The rotary connector according to claim 5, wherein said pressingmember includes an elastic portion having elasticity and presses saidflexible cable via said elastic portion.
 8. The rotary connectoraccording to claim 1, wherein said temperature detection means iscomposed of a temperature sensor.
 9. The rotary connector according toclaim 7, wherein said temperature detection means is composed of atemperature sensor.
 10. The rotary connector according to claim 1,wherein said temperature detection means is composed of a thermistor.11. The rotary connector according to claim 7, wherein said temperaturedetection means is composed of a thermistor.
 12. A rotary connectorcomprising: a stationary housing; a movable housing provided on saidstationary housing so as to be rotatable relatively thereto; a flexiblecable accommodated within a housing section formed between saidstationary housing and said movable housing; and lead blocks connectedto both ends of said flexible cable, respectively, wherein said rotaryconnector further comprises temperature detection means for detecting atemperature of said flexible cable near a connection part locatedbetween said flexible cable and one of said lead blocks.
 13. The rotaryconnector according to claim 12, wherein said temperature detectionmeans is provided on an area of said flexible cable, said areacorresponding to a position of said flexible cable being placed on saidlead block.
 14. The rotary connector according to claim 12, wherein saidtemperature detection means is provided in said lead block.
 15. Therotary connector according to claim 12, wherein said temperaturedetection means is composed of a temperature sensor.
 16. The rotaryconnector according to claim 13, wherein said temperature detectionmeans is composed of a temperature sensor.
 17. The rotary connectoraccording to claim 14, wherein said temperature detection means iscomposed of a temperature sensor.
 18. The rotary connector according toclaim 12, wherein said temperature detection means is composed of athermistor.
 19. The rotary connector according to claim 13, wherein saidtemperature detection means is composed of a thermistor.
 20. The rotaryconnector according to claim 14, wherein said temperature detectionmeans is composed of a thermistor.